Whisk together the flour, baking powder, baking soda, and salt. Set aside.

Using an electric mixer on medium speed, beat the butter, and sugar until light and fluffy. Add the eggs one at a time, mixing well after each addition. Mix in the cooled chocolate and vanilla.

Reduce mixer speed to low. Add the flour mixture in three portions, alternating with two portions of the buttermilk. Mix just until combined.

Transfer the batter to the prepared pan and spread evenly. Bake 25 to 40 minutes, or until a pick inserted into the center comes out clean.

Place the pan on a wire rack, and allow the cake to cool for 10 minutes. Then use a skewer, the end of a mixer beater, or the end of a wooden spoon to poke holes about 3/4 inches apart all over the surface of the cake.

Mix together the condensed milk and caramel. Spoon or pour over the warm cake. Spread as needed to cover the entire cake. Allow the cake to cool completely. 

Sprinkle half of the Butterfinger pieces over the cooled cake.

Using an electric mixer on medium speed, beat the cream cheese and peanut butter until creamy. (You can use a regular beater attachment or a whisk attachment.) Add the sugar and vanilla, and continue mixing until thoroughly combined and smooth. 

Switch to a whisk attachment, and mix on low speed as you slowly, steadily add the cream. Then increase the mixer speed to high and mix until stiff peaks form.

Spread the frosting on top of the cake. Sprinkle the remaining Butterfinger pieces over the frosting.